FENET Noordwijk Oct2003 MPA Steelant

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Division of Propulsion and Aerothermodynamics

E S T E C

CFD Analysis of Rocket Engine

Combustion Chambers

J. Steelant

TOS-MPA

ESA - ESTEC

Acknowledgement: R. Schmehl

Noordwijk

The Netherlands


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ESTEC, 9-10th ofOctober 2003

Multi-Physics in Rocket EnginesJ. Steelant

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Aestus (Ariane 5)

Avum (Vega)

Oxidizer dome

Fuel feed line

Cooling channels

Combustion chamber

Injectors

Application: Start-Up of Upper Stage Engines


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Multi-physical phenomena during start-up of LRE

1. Priming of feed lines and domes during start-up:

a. Waterhammer: pressure and expansion waves

b. Phase change i.c.w. cavitation

c. Absorption/desorption of pressurant (Helium)

2. Injection of liquid fuel and oxidizer into the combustion chamber:

a. Atomization evolution in near vacuum conditions

b. Vaporization modes in near vacuum conditionsc. Droplet wall impact and break-up processes


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Study: priming effects

in vacuum

1. Waterhammer with phase change

2. Unsteady injection process

3. Checking coupling with CC-

instabilities modes


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CFD-Analysis (1/3)1. Geometrical aspects

- axisymmetric fuel dome with annular injector slits

- spatial : 20K nodes; temporal: 1 sec

P9D1

P_cent


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CFD-Analysis (2/3)2. Numerical aspects

- Spatial: 3rd order Smart-scheme

- Time: backward Euler (1st order)

- Solver: Pressure-Correction method

3. Physical modelling:

- Transient laminar and isothermal Navier-Stokes equations

- Vapor transport equations:

MMH vaporization/condensation & presence of

non-condensable gas.


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CFD-Analysis (3/3)Vapor transport equation: f = vapour mass fraction

expressions for Re and Rcderived from Rayleigh-Plessetequation with:

where Ce, Cs = phase change rate coefficients

= surface tension

psat = saturation pressure

Vch = characteristic velocity

feRRffu

t

f+=+

)()(

r

)1(3

2f

ppVCR

l

satlv

chee

=

f

ppVCR

l

sat

lvch

cc

=

3

2


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Evolution of void fraction


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Spectral analysis: CFD result for 50mg N2/kg MMH


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Study: injection processes in near vacuum

1. Thermodynamic behaviour of a liquid jet into near vacuum

2. Atomization behaviour of a liquid jet in near vacuum

3. Transport and deformation of atomized jets (spray)


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Thermodynamic behaviour in near vacuum: flashing


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Flash vaporization model


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Flash vaporization in near vacuum


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Transport and deformation of atomized jets


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Wall impact, deposition and rebounce


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Wall deposition rate


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Conclusion

1. Multiphysical processes in LRE

a. Phase change icw waterhammer, cavitation, absorption,during priming

b. Processes during injection Flashing atomization & vaporization

Primary and secondary break-up of jets

Wall deposition/interaction of droplets

2. Modelling and numerical simulation allows qualitative and/orquantitative analysis of processes difficult to analyseexperimentally

FENET Noordwijk Oct2003 MPA Steelant

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